Textured protein materials which simulate meat, i.e. meat analogs, are well known in the art. These materials have been available for several decades. Meat analogs are prepared by texturizing a protein source such as a vegetable protein, single cell proteins, mixtures of vegetable protein and meat, keratin and other protein sources. The textured product is prepared by extrusion cooking, by protein fiber formation, spinning, or by shaping the protein. The small particles of textured protein are often agglomerated, i.e. held together by a binder such as egg white, to prepare a simulated meat product. The binder is usually heat-set. Various methods have been proposed for heat setting proteins, and in some cases for texturizing, the protein.
Frying is one mode of heat setting textured vegetable protein meat analogs and shaped protein products. See for example, U.S. Pat. No. 3,950,550, issued to Katayama, 1976, which discloses fried tofu product. Tofu is kneaded and shaped either as a sheet or extruded into various forms. The product is then automatically fried at two different temperatures, the first stage at 100.degree. C. to 135.degree. C., and the second stage at 135.degree. C. to 200.degree. C.
Other hydrated vegetable protein materials are fried in a continuous mass. Small particles are obtained from this mass. See for example, U.S. Pat. No. 3,962,335 and U.S. Pat. No. 3,962,481, issued to Kumar, 1976.
Bacon-like analog products are made from two protein doughs which are co-extruded and then fried. Patents related to bacon analogs are U.S. Pat. No. 3,999,474 issued to Sinkovitch et al, 1976 and U.S. Pat. No. 4,166,138 issued to Ziminski et al, 1979. Frying also reduces the off-flavor of textured soy protein products. An expanded soy isolate product was extruded and then fried to reduce both the sulfur and bitter protein flavors (Canadian Pat. No. 1,018,389 issued to Graham et al, 1977).
None of these patents, however, discloses a method for controlling the particle size of the analog as it is continuously fed into the fryer. The prior art products are pressed analog or previously shaped analog which are either reduced in size after frying or used in the form in which it emerges from the fryer.
It has been found that the particle size distribution of the meat analog, particularly when it is used as a replacement for ground beef in a sauce, should not be of a uniform size distribution. Consumers prefer a particle size distribution which includes fine, small, medium particles, and large particles. It is difficult to obtain this particle size distribution in a continuation fryer because the wet agglomerate has to be broken up into discrete particles before or during frying. These same problems occur when the textured protein is heat-set using microwave energy or radiant heat, as in a continuous oven.
The object of the present invention therefore is to provide an improved continuous frying method for textured protein wherein the particle size of the textured protein is controlled to produce a meat analog having a particle size distribution ranging from fine to large particles.
It is also an object of this invention to provide a method for continuously forming an agglomerated textured protein in a layer, the agglomerate layer having a constant bulk density and thickness, and then transferring this layer onto a continuous belt as discrete random size particles which may or may not be in contact with one another as chance dictates. The continuous belt then passes through a heat source to heat-set the analog particles.
These and other objects will become apparent from reading the description which follows.
All percentages are by weight unless otherwise disclosed.